Earth formations may be used for various purposes such as hydrocarbon production, geothermal production, and carbon dioxide sequestration. In order to efficiently use an earth formation, the formation is characterized by performing measurements of many different properties using one or more tools conveyed through a borehole penetrating the formation. One category of tools is acoustic tools that use sound waves to perform various measurements such as imaging a wall of the borehole to determine borehole rugosity as one example. Under certain circumstances, conveying a tool through the borehole for logging purposes may require that other borehole activities be suspended while the logging is taking place. This, unfortunately, can lead to increased production or exploration costs. Hence, it would be well received in the drilling industry if acoustic downhole tools were developed that reduce the amount of time required to perform downhole acoustic measurements.